It's real. It's on the White House Website. And it basically asks that signers be put on a list, kind of like the Do Not Call list, except it requests that there be a list of people who don't want our government to kill us without due process. Here's the actual text from the petition page at whitehouse.gov:
The New York Times reports that President Obama has created an official “kill list” that he uses to personally order the assassination of American citizens. Considering that the government already has a “Do Not Call” list and a “No Fly” list, we hereby request that the White House create a “Do Not Kill” list in which American citizens can sign up to avoid being put on the president’s “kill list” and therefore avoid being executed without indictment, judge, jury, trial or due process of law.
The idea is already drawing coverage in the world media. It's a capital idea. I'm signing. I think you should too. And I think it would be just lovely if instead of 25,000 signatures by June 29, there were 25 million. Maybe our illustrious "leaders" would start to feel a little nervous about a few million peasants showing up outside their Washington apartments with pitchforks.